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  1. KrisBlueNZ

    automatic light and curtain control circuit

    I know, but it might be simpler to have a slipping cord than adding two limit switches with associted wiring. Depends on the setup.
  2. KrisBlueNZ

    Shadow signal

    Are you sure you understand the requirements? Can you draw up a schematic? That won't happen unless the frequency suddenly increases by a factor of 5 or more within the space of one cycle. Can that even happen? I'm having a "bit of bother" with my circuit. My oscillators are amplifying and my...
  3. KrisBlueNZ

    Shadow signal

    Thanks :-) But I should have been more diplomatic. Yes I agree that a microcontroller would be appropriate, but I'm working on the capacitor charge/discharge method that I mentioned in post #10 and Laplace described in more detail in post #17. When I finalise and post my circuit, perhaps...
  4. KrisBlueNZ

    Designing a Time Delayed Relay

    No. Which side you call the top and which side you call the bottom depends on your point of view, but in designs where space is tight, it's common to put the THT and tall parts on one side of the the board, and all or most of the SMT parts (low profile) on the other, in the gaps under the large...
  5. KrisBlueNZ

    automatic light and curtain control circuit

    OK, that's fair enough. So a gate would be needed. She should know about them, but sometimes it might be simpler to just generate fixed run drations and let a cord slip somewhere. I think a 40106 or some 4093s would be the simplest, most compact, and easiest to understand option for control...
  6. KrisBlueNZ

    Designing a Time Delayed Relay

    Unless you put ALL of the tall items on the underside, right?
  7. KrisBlueNZ

    automatic light and curtain control circuit

    Oops! I apologise for calling you a "him"! The 555 data sheet shouldn't say that the supply voltage should be 5V. The normal range IIRC is 4.5~15V and 12V is very often used with a 555. OK I don't understand the purpose of the lamp. How will it be labelled? What will it be used for? And when...
  8. KrisBlueNZ

    Designing a Time Delayed Relay

    Yes, I see your point. You might like to put the large THT components on the underside - the transformer and the relay, and perhaps the connectors. Assuming the transformer sits well above the board, you can even put THT components on the opposite side of the board - the electrolytics, for...
  9. KrisBlueNZ

    schmitt trigger

    Your circuit in post #4, with a TL061, should work fine. Double-check your construction against the pinout in the TL061 data sheet, and make sure you've numbered the pins like this.
  10. KrisBlueNZ

    Adjustable brightness torch??

    Actually, back EMF is not the best name to use for this phenomenon because back EMF occurs whenever the magnetic field in an inductor is changing, not just when it is collapsing. The proper name is inductive kickback. It's also called flyback, inductive kick, and inductive spike. It's a bit...
  11. KrisBlueNZ

    Shadow signal

    Oh, OK. Sorry, "I have no idea how your circuit is supposed to work" was a bit insulting!
  12. KrisBlueNZ

    Shadow signal

    OK well I have no idea how your circuit is supposed to work. I think the simplest approach would be to charge a capacitor with a constant current during the input pulse then discharge it with an equal current until it hits the initial voltage, to determine the width of the pulse. There are...
  13. KrisBlueNZ

    Shadow signal

    Can you answer my other question as well? Also, how accurate do you need the second pulse duration to be? What percentage of timing error is allowable?
  14. KrisBlueNZ

    Capacitive Reactance Circuit

    I think the eBay page said 300 mA ±10% over the full input voltage range.
  15. KrisBlueNZ

    Shadow signal

    What is the range of pulse widths? What is the minimum and maximum pulse repetition frequency?
  16. KrisBlueNZ

    design buck converter with arduino controlling pwm

    The IR2101 will work fine. You will need another supply voltage of around +12V for it - you can use a 7812 supplied from the 24V input. You don't use the low-side switch. The bootstrap circuit (diode and capacitor) around the IR2101 will ensure that the MOSFET gate is pulled up to about +34V to...
  17. KrisBlueNZ

    automatic light and curtain control circuit

    Great post Steve! And lucky you posted it before I posted my response... I didn't realise this was homework and I was going to give him some direct answers. Your approach is much better. BTW my 'notsohot' design you linkd is not one of my more readable schematics... I squeezed it a bit to make...
  18. KrisBlueNZ

    Capacitive Reactance Circuit

    Mine arrived a few days ago and looks exactly the same as yours. The IC is also a BP9021. Thanks for the link to the data sheet. There's no English version available (yet) but here's what Google Translate made of the Chinese main summary text. I may have a look at the output ripple at some...
  19. KrisBlueNZ

    Solar Charger schematic

    LOL at the footnote to the project: In other words, Mr. Mohankumar is well known for designing poor and sometimes unworkable circuits and has been kicked off the site, but we're still going to present this design of his, and leave you to try to make it work!
  20. KrisBlueNZ

    Help Getting Started with PIC Microcontrollers

    No. The code generated for if/then/else doesn't use the stack. test the conditon if the condition is false, go to false label execute the then clause go to done label false: execute the else clause done: continue... That's right. Function C couldn't call anything - not another function in the...
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